1. Field of the Invention
The invention relates to an infection-preventing catheter arrangement with a catheter which exhibits a rigid or flexible catheter tube with a connection piece furnished at the distal end of the catheter tube.
2. Brief Description of the Background of the Invention Including Prior Art
An important and frequently life-endangering complication in connection with the use of intravascular catheters comprises the occurrence of catheter-caused infections. The infection rate increases the longer the catheter remains in the body. For demonstrating the explosive importance of this problem, reference is made to a study, which is representative for a large number of similar investigations and which appeared in the "American Journal of Medicine" in 1981. According to this study, about 20,000 death cases occur each year in the United States, which death cases are attributed to catheter-caused infections. The research programs which have been performed and which are still currently being performed relative to this problem field worldwide are correspondingly numerous and varied.
It is known that pathogenic bacteria, once penetrated into the catheter, find ideal growth conditions there and they can uninhibitedly reproduce in an environment and under conditions of complete absence of antibodies, immune bodies or defense mechanisms present in the body. The result is a washing in of entire bacteria colonies into the body of the patient and thus causing a bacteriaemia, bacillaemia, or, respectively, sepsis, blood poisoning.
The past attempts to decrease the infection rate are substantially based on four different propositions, which have the goal, first to kill the bacteria, second to prevent access into the interior of the catheter to the germs, third to employ special catheter materials which make a bacteria invasion and bacteria appositioning more difficult, and fourth, combinations of these three methods.
Four United States patents are in particular to be noted with respect to the first proposition.
A catheter is described in the U.S. Pat. No. 4,623,329, where the catheter tube wall is furnished with capillaries containing germicidal agents. The agents pass by diffusion into the interior of the catheter. The effect which can be achieved in this manner, however, is very limited because the concentration of the agent is too low. In addition, the non-uniform release of the agents as well as the complicated construction of this special catheter are disadvantageous.
Technical solutions for closure cap systems with an agent reservoir or, respectively, an agent-absorbing wall material are known from the U.S. Pat. Nos. 4,432,764, 4,440,207, and 4,624,664. Said closure cap systems can be attached to the rearward connection piece during non-use of the catheter. Such closure caps fight however only a contamination of the catheter closure possibly occurring upon removal of the infusion tube and they do not fight the bacteria infiltrating through the catheter tube tip. It is known however, that an increasing deposit of bacteria occurs in particular at the tip of the catheter tube.
The second proposition is based on obtaining the goal to prevent bacteria from accessing the interior of the catheter tube. A duck-bill valve is known from the German Printed Patent Document DE-OS 35 04 661. This duck-bill valve allows the entrance of the medication or, respectively, of the solutions to be injected into the vessels as a one-way valve. On the other hand, however, the duck-bill valve prevents that liquids from the vessels can flow back into the catheter. One-way valves however are associated in principle with the disadvantage that the testing of the position of the catheter in a blood vessel is not possible based on an aspiration of blood.
It is furthermore conventional to insert a mandrin into the catheter tube in order to close the catheter tube during an intermittent injection. A catheter device with a mandrin is described in the German Printed Patent Document DE-OS 37 21 299. The medication, injected through an auxiliary injection port, flows through a fluid channel between mandrin and catheter tube and the medication exits through a valve from the catheter tube. Since the mandrin does not have to be removed any more from the catheter tube for an injection, a contamination of the lumen of the catheter tube is substantially avoided.
According to the proposals of the two precedingly recited German Printed Patent Documents, valves are employed which in fact prevent the infiltration of body liquid, but which do not prevent the infiltration of bacteria. A lack in sealing capacity and, in particular, the opening of the valve during the injection lead to the situation that some bacteria still pass into the catheter tube. However, already a few bacteria are sufficient to cause an infection danger.
A third possibility for decreasing the infection danger comprises to employ an antiseptic material for the catheter tube of the catheter or, respectively, to coat the catheter tube at least in part with such a material.
A bacteria-resisting mixture made of biocompatible base material and antibiotic metals is taught in the U.S. Pat. No. 4,677,143. It is proposed in the U.S. Pat. No. 4,642,104 to chemically bind an antimicrobic material to a base polymer. However, it has been shown in the clinical practice that more tissue damages, in particular irritations and inflammations, are caused by these catheters than by non-treated catheters. In addition, there exists the danger of development of a resistance by the bacteria against the antimicrobic metal.
A fourth method of approaching the problem is based on a combination of the above recited and discussed first three solution propositions.
Catheters or, respectively, additional units for catheters are described in the German Printed Patent Document DE-OS 37 47 548 and in the U.S. Pat. No. 4,676,782, which have the goal to prevent microbes from accessing through the implantation wounds, by employing locally antibiotics-containing materials. For this purpose, according to the German Printed Patent Document DE-OS 37 47 548, the outer surface of the catheter tube section, disposed in the region of the body opening, is furnished with a hydrophobic microbe-absorbing coating. The effect of the additional unit for arbitrarily commercially available catheters, described in the U.S. Pat. No. 4,676,782, is based on a similar principle, a separate sleeve for encasing the puncture region is proposed. This device, also known under the designation VITA CUFF, however, similar to the variant, described in the German Printed Patent Document has only a local effect and therefore brings only a partial success.
All conventionally known, above discussed measures for the decrease and the prevention of catheter-caused infections have so far only led to very small successes.
In addition, the injection of an antibiotic solution into the catheter is disadvantageous, where the injected volume is much larger than the catheter volume, as described in B. Messing, O. Peitra, A. Debure, M. Beliah, J. Bernier, entitled Antibiotic-Lock Technique: a new approach to optimal therapy for catheter-related sepsis in homeparenteral nutrition patients, J. Parenter Enteral Nutr. 1988; 12:185-189. Based on the penetration of the excessive antibiotic solution into the organism, the concentration of the antibiotic necessarily has to be kept so low that no toxic side effects or bacterial resistances can occur. This is associated with the result that the germicidal effect of the antibiotic solution remaining in the catheter between two injections, is insufficient to completely kill all bacteria adhering at the inner wall of the catheter.
The prevention of catheter-caused infections is further discussed in G. Palm, W. Boemke, H. W. Reinhardt in Journal "Der Anaesthesist," Vol. 38, 1989, Supplement 1, page 129.